Maritime current power plants in form of free-standing units with rotor-like water turbines for generating power from a watercourse or a maritime current, especially a tidal current, are known. An arrangement without damming structures opens up numerous installation locations especially close to the coast for which barrages cannot be produced in an economically viable manner. Furthermore, the typically fully immersing units do not represent an obstruction to shipping and do not represent any danger for the fish stocks due to the low rotational speed of the rotor-like water turbines. The disadvantageous aspect in the design concept of free-standing maritime current power plants is the necessity that every single unit needs to be configured for rarely occurring peaks in the loading because it is not possible to use the possibility provided for barrages to remove individual water turbines from the flow by blocking the conduction of the water.
One possibility for regulating the speed of generic units is to rotatably fasten the rotor blades of the water turbine to a hub component. For the purpose of reducing the load in the event of strong inflow, the rotor blades can then be moved to the feathering pitch. This approach leads to a constructively complex attachment of the rotor blades however. It needs to be considered that the actuators and bearing components required for the adjustment of the rotor blades need to be arranged in a fail-proof manner because in the event of an erroneous position of the blades there is the likelihood of a loss of the rotor blade. Furthermore, a rotatable rotor blade fixing represents a component which requires high amount of maintenance especially for a location in the sea with respect to problems concerning corrosion and maritime growth, so that the constructively simple approach of a torsion-proof fixing of the rotor blades to a hub element is preferred.
For the purpose of securely configuring the unit, it is necessary to additionally consider the expected meteorological conditions in addition to the cycles of the driving flow. In the case of the tidal flow, the inflow caused by ebb-tide and flood-tide can be influenced by wind and wave motions. This relates especially to areas close to the surface. Furthermore, the contour of the seabed needs to be taken into account, with peak loads having to be expected depending on the current and weather conditions.
If several maritime current power plants are combined into a maritime current power plant park, it is advantageous for economic reasons to use identical units. This simplifies production and installation of the maritime current power plants. Furthermore, the interconnection to the grid and the maintenance of the units can be standardized and be performed with uniform maritime vehicles for salvaging. The inflow conditions will vary within a maritime current power plant park depending on the respective installation location, so that the uniform units need to be adjusted to the maximum load which may theoretically be expected in the part in total. Most units of a maritime current power plant park are consequently designed with an overdimensioned security reserve, so that this would lead to constructively complex maritime current power plants with reduced efficiency.